The present invention relates to means for seating a gasket in a groove. More specifically, it concerns means designed (i) to manipulate a deformable insert capable of regaining its original shape--that of a circular ring of any cross-section whatsoever--and of forming a seal, and (ii) to set said insert into place in a matching recess, such as a groove, located within a hollow cylinder of revolution such as a cylindrical pipe coupling or the socket at the end of a pipe.
Seating a circular ring in a matching recess requires that the ring be deformed because its outer diameter is necessarily greater than the inner diameter of the cylindrical space containing the matching recess into which the ring will be seated.
In the remainder of this specification, the word gasket will designate the ring-shaped insert, while the word groove shall designate a matching recess in the hollow cylinder. This simplication corresponds to the terms of the most frequent use of the invention, i.e., installing a flexible circular gasket within a groove located inside a hollow cylinder.
Altering the shape of the gasket makes it possible to push the latter into a cylindrical space having a diameter smaller than that of the gasket until a point opposite the groove is reached, at which point the pressure on the gasket is relaxed and the latter regains its initial shape and becomes seated in the groove. In other words, the deformation creates a temporary reduction in the outer diameter of the gasket at rest. In general, annular gaskets are used to seal the outer limit of two areas traversed by a revolving shaft or by a control rod that is allowed to rotate at least during assembly.
In the particular case of joining two pipes, the gasket is installed ahead of time in the groove of the coupling or socket, and the pipes are fitted together on the site by a simple translational movement, since their size makes them difficult to rotate.
In this field, portable and nonportable tools are presently used to compress gaskets and to introduce them into the cylindrical space around the groove. Most of these tools produce a cardioid deformation of the circular gasket, so that the latter comes to resemble two lobes separated by an invagination induced by a digit or prong that is perpendicular to the plane of the gasket at rest, which, by a radial motion toward the center of the gasket, draws the latter inward, while at least two studs parallel to the prong and situated inside the gasket guide and hold the latter.
Tools of the type described above have a number of drawbacks. First, it is difficult to deform the gasket in a single plane, especially if its cross-section is not circular, since deformation normally produces a three-dimensional curve. This makes it more difficult to get the gasket seated in the groove around its entire circumference, and inaccurate positioning must be corrected manually.
The second drawback lies in the fact that when one withdraws the prong that produces the deformation, it is very difficult to prevent the prong from drawing the deformed portion of the gasket along with it in the direction of withdrawal. This is another source of improper positioning in the groove.
Yet another disadvantage arises from the radical deformation of the gasket, which requires the application of considerable force that may cause damage (e.g., cracks, tears, permanent changes in the shape of the insert). These can be prejudicial to the proper functioning of the gasket, particularly in its leakproofing capacities.
As a result of all of these drawbacks taken together, it is difficult to automate the installation of gaskets using three-point tooling that produces cardioid deformation.